Web browsers have a folder in which contains certain items that have been downloaded are stored for future use. Photo's, graphic images like buttons and icons and entire web pages are some of the which are saved or cached. When you visit a webpage the browser checks if a copy of the files on the page is in its cache already. If it is already there, it will save the visitor some downloading and make webpages load faster as the files are already there. Some browsers refer to it's cache as Temporary Internet Files.
When using online software such as NewZapp, saved webpages can cause problems while making changes to emails and navigating around your account. In order for NewZapp to work at its best we recommend that you clear your cache regularly. This way you are using the most recent webpages from NewZapp rather than using old files that have been stored in your cache.
You can find instructions on how to clear your cache here.